Extensible work tower



June 18, 1940. L. E. ERlcKsoN er Ax.- 2,204,671

EXTENS Iv-BLE WORK 'rown Filed April 15. 1939 s sheets-sheet 5 June 18, l1940. L. E. ERICKSON ET Al, 2,204,671

EXTENSIBLE. WORK' TQWER s sheets-sheet 4 Filed April I5, 1959 4 hummm 11"" zzopd JM 0257012 June 18, 1940. L. E. ERICKSON `rer AL 2,204,671

June 18, 1940.

L, E. ERICKSON Er AL 2,204,671

EXTENSIELE WORK TOWER Filed April 1s, 1939; e sheets-sheet s lllllillliiiliiilll" 122 Patented June 18, 1940 PA'rErr4 OFFICE EXTENSIBLE WORK TOWER Leonard E. Erickson and Buford W.

Olson,

, Minneapolis, Minn., usignorsto Chas. Olson i Sons, Incorporated, Minneapolis, Minn., a corporation of Minnesota j Application April 15, 1939, serial No. zsaosz 1 claims. (crau-s) This invention relates broadly to vertically extensible work towers or scaifoldings.

The extensible tower isl well adapted for use in connection with a truck,` and which arrangement is especially serviceable as a highly eilicient work truck for repairing or installing trolley wires or the like. l

A truck of this kind when' used in connection with trolley lines or other high power electric l0 lines should have highly eicient insulation between the ground and the Work top or work platform of the upper section of the tower. The extensiblesections of the tower should have great lateral stability and simple, and eiiicient means should be provided for quickly imparting the extending` and contracting movements to the tower. i

The above and other important and novel features are accomplished in this invention. Some of the features of the invention especially adapt the tower for use in connection with high power electric lines. Also certain ofthe features are `highly desirable for use in connection with stationary vertically extensible towers or repair 25, scaiolding.

When the extensible tower is used on a truck itis also highly important that no part of the tower extends below the chassis of the truck and that the tower when contracted, `will be` brought down to such vertical dimensions that it willreadily pass under bridges, through culverts andthe like. `From the above it will be understood that the invention is capable of a wide range of uses, u to wit; for various services where extensible work devices are required. The accompanying drawings illustrate a commercialform of the extensible tower applied to a truck such as an automobile or motor proo pelled truck. p

Referring to the drawings wherein like characters indicate like partsthroughout the several views: p Fig. l is a perspective illustrating the tower 45 applied to an auto truck with thetower contracted to itslowest condition; i i,

Fig. 2 is a side elevation; ofthe parts shown in Fig.` 1 but with the tower `vertically extended; l 3 is a side` elevation showing the tower 50 extended but removed from the truck, with some parts broken away; l

Fig. 4 is an enlarged fragmentary section taken on the line 4 4 of Fig. 3; Fig. 5 is a horizontal sectiontaken on the line u l-i of Fig. 3;

corner posts of which are arranged to Fig. 6 is a perspective with some parts broken away showing the lower section of the tower;

Fig. 'l is a perspective showing the center or -second section of the tower: and

anauto. truck which may take various forms, but l0` is preferably designed to `carry `various tools or devices useful in performing the work for which the equipment is designed to perform.

Of the parts of the truck illustrated, it is only desirable for the purpose of this case to l5 brieiiy note the truck wheels III, the chassis frame II and the truck body I2, which latter is formed on its top with a xed elevated deck I3. lncidentally, it will be further noted that the truck at its rear is shown as provided with upright ladder I4 that extends from rear platform I5to a point above the rear of the upper deck i3. The numeral I6 indicates portable ladders shown as carried by the truck, 1blut which form no part of the present inven- 25 Directing attention particularly to Figs. 3 and 6, it will be noted thatthe lower section A of the tower is rigidly secured to and carried directly on the rear ends of the chassis beams II. This 3o lower section A is a rectangular steel structure made up as shown of rectangular angle iron or steel beams I'l that are directly secured upon the chassis beams Il and cross frame members IIa that span the beams II. Angle iron corner posts I8 are rigidly secured to `ancl rise from the corner base frame Il. At their extreme upper ends the corner posts I8 are tied together by a rectangular steel frame I9 and at their intermediate portions they are tied together by a similar rectangular steel vframe 20. The frame work of this lower section A is shown as further reenforced by oblique angle bars 2I.

'I'he second or intermediate section `i3 of the tower is a rectangular skeleton member, the

slide in the channels of and be guided by the corner posts I8. This intermediate section B has corner posts 22 which for an important purposealready indicated and hereinafter more fully discussed, are of material that is a good electrical insulator. In practice, and preferably, these posts 22 are made of wood such as oak. At their lower ends these posts 22 are rigidly secured to metal tie plates 23; at their intermediate pora lower very elfectually insulating thef'upierumetalliic' Fig. 4,' that 'the metal corner posts ;28'="are"'stee `or metal angle barsf havingoutwardly':exposedt4 tions are rigidly secured to and tied together by metal tie plates 24; and at their upper ends are rigidly secured to and tied together by tie plates 25. The said tie plates 23, 24 and 2li-Ay are in rectangular arrangement and are applied to and secured to the outer faces.- of tlieposts 22 by rivets, bolts or the like and advisably also by gussets 26, which latter are bolted to said posts and electrically welded to the respective tie plates. The lower tie plates 23 are further reinforced by and either formed integral with or spot welded tohorizontally disposed inwardly projecting metal tie plates 21.

tion C is further reinforced by oblique metalr.-b'ar s 33.

It is now important to n ote, see particularl channels. that engagerthe 4-inwardly projecting corner andface-portions'of the wooden posts 22 of the intermediate or second section-v-l thereby section C from vall grounded connection with the lower portion of the tower, the, truckand the.-

stance is section C, carries a horizontally rovv tatable working platform. "In the drawings -this-4` working platform is indicated as an entirety'by the numerals 34 and it has such length that it will' project a very considerable distance, from-v To stably support the working platform 34 from the tower, a turntable structure'v the tower.

is employed. As shown, this turntable involves a lower annular bearing plate 35 rigidly secured!v on the top of the section C, .and an 'upper annular bearing plate 36 rigidly secured to the bottom of theworking platform 34 near one end thereof.

When the working platform 34 is elevated, it is adapted to be turned to any desired position, but when the tower is lowered, the projecting portion of this platform will fall between laterally spaced stop brackets 31 rigidly secured on the deck and will then be held against lateral pivotal movements and in direct line with the truck body so that it will not accidentally move during transportation.

The power actuating lifting means for the movable sections of the tower is highly important and considered novel. The primary lifting element is an upright hydraulic cylinder 38 which,

for an important purpose, is located at the axis through the head of the piston. 'I'he cylinder 38,

'in vertical extent, is somewhat less than the height of the lower section -A and also somewhat less than the height of either of the movable towersections B 4and C and this4 feature, as will hereinafter appear, is important. y The piston -40 vacts 'primarily ltou raise 'the secdnd-section -.B, and to. accomplish this, with-the cylinder 38 located within the lower section A and-above'the chassis of the truck, the upper end of the piston is connected to the bottom. of.` the section B by a strong, centrally located, in-J verted U-shaped hanger. frame- 4If. hanger' frame is a-stro'ng metalfstructurepreferablyfmade up vof :channelbarsSrigidlyeonnected at their Vupper -end`s. by;a..transvers e portion. The-lower:

`with' thelsectionf nautici-move' in respecta the latter, a v multiplying motion transmitting .mechanisxn isl'provided.FThis-mechanism, as best'` 'shown in Figsi3, 4.and`6,"inv olves cables-anchored@ to or in respect to thabottomgofsection A, passedA twtlie" bottom fof' Athefsection- C. These -soecalled cables',.vras herein illustrated, involve chains: or

tions u: #I n'; this arrangements isule 1ower ends oftlegrodfportins 44j'th'at `ar'eanchored at 45 tothe-bottoni'of the tower `section A, see particularly Fig. 6. The flexible sections 43 are passediover guide sheaves 4G, shown as journalled to the upper tie plates or bars 25..of the intermediate section B and to supplemental bearing plates 41, see particularly Figs. 5 and "7, which latter are rigidly'4 secured to. theinner faces' of said tie plates 25. l

In this arrangement there are four guide sheaves 46 and four cables, and it is highly importantto note that the depending portions of the'exible cable sections 43 are attached to the four corners loi? the bottom of the section C at i the four corners of the said section C, so that the liftingor supporting `action of the section.C is equally distributed at the four corners thereof. The long depending and more or less rigid portions of the lifting cables are shown as provided I with insulators 48 and turnbuckles 49.

The motive power here preferably employed is a fluid such as oil, indicated by the character Y, which will bel circulated from the one end to the other of the cylinder 38 under the action l of suitable means such as a pump, not shown, but which would operate through a conducting pipe 60 shown in Fig. 6.

It may be noted that the lower portions 44 of .the lifting cables are passed through clearance l holes 5l in the frame bottom plates 21.

Summary of operation Fig. 1 shows the towercontracted or lowered and the truckin condition for traveling to the 1 place where it is to be used. Figs. 2 and 3 show the tower elevated. The primary power from the cylinder and piston motor, under the action of hydraulic pressure, applies the power to primarily lift the second tower section B, with the force i applied at the center or axis of the latter,` so that the rlifting strain is distributed evenly at the four corners of the said section B. The four pulleys 46, of course, are raised to the same extent as the se'ctlon'B, but the cable being an-V1 chored at one end and attached to the third or uppersection C at the lowerportion of the latter, will cause the said section C to be elevated twice as far as'the section B, or in other words, the section C will be given, in respect to section B, the same amount ot vertical movement that is given to lthe section B, in respect to the fixed section A. These four,` cables attached at the four corners of the section C evenly lift the said section C and prevent binding of the section C i in respect to the guides afforded by the section B.

The insulated or insulating posts 22 afford small guiding surfaces for the angle iron posts 23 of uppersection C, and all of the adjustments of the sections of the tower afford a high grade electrical insulation between the upper tower section and the section B. 0f course, this insulation completely insulate? the working platform 34 from the truck and from the ground and thus preventsthose working on the platform 34 from being electrically grounded from high tension wires or the like.

As already indicated, the maximum movement of the piston 40 within the cylinder 38 is considerably less than the otherwise possible movement of the section B, in respect to section A, and section C in respect to section B. For example, Fig. 3 illustrates about the maximum possible vertical extension` of the tower under the movement of the piston in respect to the cylinder. 'I'his always maintains sufficient telescoping contact between the sections to maintain the desired lateral stability of the tower and to prevent undue strains on `the tower sections caused by weight that may be on the extended portion of the working platform 34.

0f course, the movement of the piston in respect to the cylinder, and hence the extension of the tower, may be limited to any desired extent, by` control of the oil or liquid to and fromthe opposite ends of the cylinder. Valve mechanism and co-operating connections for causing reciprocations of pistons within cylinders are well known, and as far as this invention is concerned, may take any of the well known and suitable forms.

Again it is also important to note `that the e tower extends through the deck I3, so that workmen reaching this deck I3 from the conveniently located ladder Il, or otherwise, may very easily mount the working platform 3l, when the tower is contracted or lowered, as shown in Fig. 1. 'I'he inverted lifting frame applies the lifting force to the bottom or lower portion of the second section B.

Also, from the foregoing, it will be understood that the preferred and at present commercial form of the device is capable of modifications within the scope of the invention herein disclosed and desired to be broadly claimed.

What we claim is: f

1. In a tower of the kind described, a relatively fixed lower section, a second or vertically movable section telescoped for sliding movement in said lower section, an inverted lifting frame located within said movable section with its lower portion fixed to the lower portion of said movable frame, and a power actuated lifting motor located centrally of said frames, anchored at the base of said lower frame and operative on the upper portion of said inverted lifting frame, to elevate the latter and said movable frame, in further combination with a third frame telescopically removable within said second frame, four cable guides on the upper portion of said second frame, four cables anchored at their lower ends tially rectangular relatively fixed lower frame, a

substantiallyv rectangular second frame telescopically slidable within said relatively fixed lower frame, a substantially rectangular third frame telescopically slidable within said second frame, a hydraulic power device including `a cylinder and piston, said cylinder being located within said relatively fixed lower frame and anchored at the base thereof, said piston being connected to and operative on said second frame to lift the same, and a motion multiplying connection operative under vertical movements of said second frame, to impart additional upward movement to said third frame, and in which one of said frames has corner posts with guide surfaces of electrical insulating material, and a co-operating frame has metallic corner posts engaging said insulating guide surfaces.

3. In a tower of the kind described, a substantially rectangular relatively fixed lower frame, a substantially rectangular second frame telescopically slidable within said relatively fixed lower frame, a substantially rectangular third frame telescopically slidable within said second frame, a hydraulic power device including a cylinder and piston, said cylinder being located within said relatively xed lower frame and anchored at the base thereof, said piston being connected to and operative on said second frame to lift the same, cable guides on the upper portion of said second frame, and cables passed over said cable guides, with their lower ends anchored to the base of said fixed lower frame, and having their upper ends anchored to the base of said third frame, and in which said second frame has corner posts of electrical insulating material affording guide surfaces for said third section.

4. In a tower of the kind described, a relatively fixed lower section, a second or vertically movable section telescoped for sliding movement in said lower section, an inverted lifting frame located within said movable section with its lower portion fixed to the lower portion of said movable frame, and a power actuated lifting motor located centrally of said frames, anchored at the base of said lower frame and operative on the upper portion of said inverted lifting frame, to elevate the latter and said movable frame, and in further combination with a, third frame telescopically removable within said second frame, cable guides on the upper portion of said second frame, and cables passed over said cable guides anchored at their lower ends to the base of said relatively fixed lower frame` and at their upper ends anchored to the base of said third frame, one of said frames having corner posts that afford guide surfaces and are insulated against electric current, and the co-operating section has metallic corner posts slidably engageable with said insulating surfaces.

5. In a tower of the kind described, a relatively upper portion of said inverted lifting frame, to elevate the latter and said movable frame, and in further combination with va truck on the chassis of which said rst or lower frame is `i5 anchored, said truck having a raised deck n..through which said rst or lower frame is extended.

6.' In a tower of the kind described, a relatively xed lower section, a second or vertically mov- 10 able section telescoped for sliding movement in said lower section, an inverted lifting frame located within said movable section with its lower portion xed to the lower portion of vsaid movable frame, and a power actuated lifting motor 15 located centrally of said frames.- anchored at the base of said lower frame and operative on the upper portion of said inverted lifting frame, to elevate the latter and said movable frame, and in further combination with a truck on the chassis 20 of which said rst or lower frame is anchored,

said truck having a raised deck through which said rst or lower frame is extended, and a ladder structure mounted on the rear portion oi.' said truck, extended to said deck and to the upper portion of said lower frame.

7. In a tower of the kind described, a fixed lower frame having metallic posts, a second frame having wooden posts directlyv engageable with and slidable vertically in respect to the metallic posts of said lower frame. and a third or upper frame having metallic posts directly engageable with and slidable vertically in respect to the wooden corner posts of said second frame, and thereby insulated from said lower frame and from the ground, and means for vertically moving the said second and third frames in respect to said lower frame and said third frame in respect to said second frame.

LEONARD E. ERICKSON. BUFORD W. OLSON. 

